Gas turbine engines include compressor, combustor, and turbine sections. The combustor includes fuel injectors that supply fuel for the combustion process. Variations in the calorific value of gas fuels for lean premixed combustion may require different conditions for creating the gas fuel and air mixture to meet desired emission conditions. Separate hardware for high calorific value gas fuels and for low calorific value gas fuels are used to accommodate these different conditions.
U.S. patent application publication No. 2010/0162711 to Zuo et Al. discloses primary nozzles for a Dry Low NOx (DLN) combustor that are configured to alternatively burn a first gas fuel or a second gas fuel, where the two gas fuels may have widely disparate energy content. Natural gas may be the first gas fuel and syngas may be the second gas fuel. An inner fuel circuit and an outer fuel circuit are provided to allow effective control of fuel/air mixing profiles, dynamics, primary pre-ignition and emission control by changing the fuel split between the two fuel circuits. The inner fuel circuit may be run in a diffusion combustion mode on many gas fuels.
The present disclosure is directed toward overcoming one or more of the problems discovered by the inventors.